The invention relates to torque transmitting fluid couplings, and more particularly, to the mounting of such fluid couplings.
Conventionally, fluid couplings include an output coupling member defining a fluid chamber, an input coupling member rotatably disposed within the fluid chamber and a quantity of viscous fluid contained in the fluid chamber such that rotation of the input coupling member transmits torque to the output coupling member by means of viscous shear. The input coupling member is typically mounted on an input shaft, with the opposite end of the input shaft attached to some type of input drive member such as a flange associated with the engine water pump , or a pulley driven by the engine crankshaft through one or more V-belts (U.S. Pat. Nos. 3,661,237 and 3,899,059).
It has been common practice in the art to provide ample axial separation between the pulley and the fluid coupling to facilitate access to the bolts and nuts used to attach the input shaft flange to the pulley. However, as the trend toward compact and subcompact automobiles has developed, it has become necessary to reduce the size of many of the engine accessory components, and especially their axial dimensions. This has also been true in the case of fluid couplings used in automotive applications as the drive for the vehicle radiator cooling fan.
The attempts at shortening the axial length of the entire water pump-pulley-fluid coupling assembly have included the arrangement illustrated in U.S. Pat. Nos. 4,073,370 and 3,263,783. These assemblies use an externally-threaded hub and an internally-threaded, enlarged portion on the input shaft. It is, however, undesirable to require matching threads on a coupling and the device to which the coupling is attached in instances where the two components are manufactured by unrelated companies or at separate locations.